Waste streams are commonly treated by a wide variety of solutions in order to remove organics, solids, and any other undesirable contaminants therefrom. For example, waste streams may be contacted with activated carbon for a time effective to remove organic contaminants therefrom. In some instances, activated carbon is combined with biological material for the removal of readily biodegradable organics from the waste stream. Thereafter, the resulting treated stream requires removal of suspended solids therefrom.
Conventional wisdom is that the concentration of suspended solids should be kept to a moderate level (˜8 g/L) in contact with the membrane(s) of such filtration systems. This is due to the fact that elevated solid concentrations typically result in high transmembrane pressure (TMP) during operation. When biological material is utilized, even in combination with activated carbon to remove organic contaminants, the biological material is further thought to cause a rapid rise in transmembrane pressure (TMP) due in part to the consistency of the biological material. Further, long-term operation with the membranes in direct contact with the activated carbon can result in membrane damage. Due to these potential issues, a gravity separation step to further separate solids from the fluid/material to be treated preceding the membrane unit is typically included in membrane filtration systems to reduce or prevent carbon contact with the membranes. In any case, the lower suspended solid limitations for activated carbon or activated carbon/biomass and added components (e.g., clarifiers): (i) reduce efficiency; (ii) add expense, operating time, and materials; and (iii) increase the footprint size of the treatment system. Improved fluid treatment systems that incorporate activated carbon and membrane filtration are thus needed in the art.